1. Field of the Invention
The present invention relates to novel zinc-compatible silica particulates, to a process for the preparation thereof, and to the formulation of improved dentifrice compositions therefrom, notably dentifrice compositions containing zinc values.
2. Description of the Prior Art
It is known to this art that silica is a particularly useful component in dentifrice compositions. It serves a variety of functions in such dentifrice compositions.
It serves primarily as an abrasive and polishing agent by mechanically assisting in the removal of dental plaque.
It can also serve as a thickening agent to confer predetermined rheological properties to the dentifrice, as well as an optical agent to impart desired coloration thereto.
It too is known to this art that dentifrices contain various other ingredients, in particular for the prevention of caries, to reduce the formation of dental plaque or the deposition of tartar onto the teeth. Among these other ingredients or agents, zinc is specifically representative. Other constituents are also included, such as fluorides, phosphates, pyrophosphates, polyphosphates, polyphosphonates, guanidines, in particular the bisbiguanidines, and, most typically, chlorohexidine. The various dentifrice compositions may also contain such additives as flavors, perfumes, and the like.
The presence of these agents in a dentifrice composition presents the serious problem of their compatibility, or, more correctly, their incompatibility with silica. Indeed, principally due to its absorbent properties, the silica tends to react with a number of such added agents, notably zinc values, to an extent that they are no longer available to elicit their desired therapeutic or cosmetic effects described above.